6-34 - Organic Chemistry (Mcmurry)

Question

Add curved arrows to the following polar reactions to indicate the flow of electrons in each:

(a) 

(b) 

Step-by-Step Solution

Answer

(a) 

                          Formation of carbocation

              Formation of deuterium substituted benzene

(b) 

                              Formation of chloride ion

                       Formation of 1-chloropropan-2-ol

Reaction with D-Cl

The pi-electron density of the benzene ring interacts with the D-Cl molecule to form resonance stabilized carbocation in the first step as shown:

                          Formation of carbocation

Formation of deuterium substituted benzene

The carbocation stabilized by the loss of one proton gains its aromaticity. Thus, the product deuterium substituted benzene is formed as shown:

                 Formation of deuterium substituted benzene

(b) Formation of chloride ion

The oxygen atom of the epoxide ring is first protonated by the HCl molecule along with the formation of chloride ion in the first step as shown:

                         Formation of chloride ion

Formation of 1-chloropropan-2-ol

In the second step, the chloride ion then attacks the carbon atom at the less hindered side of protonated epoxide to form 1- chloropropane-2-ol as shown:

                       Formation of 1-chloropropan-2-ol